• iter
• hydrogen combustion
• vvpss
• isotope separation
• ecosimpro
• multiflash
• UV flash

The aim of this PhD is to develop a system-software tool able to manage the multicomponent thermodynamics that can happen in the safety systems of a fusion reactor (ITER), in order to provide the designers of a common and comprehensive platform for the simulation of different safety systems, such as the Vacuum Vessel Pressure Suppression System (VVPSS).
VVPSS represent one of the safety barriers in case of accident and it shall keep vacuum vessel (VV) pressure below the atmospheric pressure and below the pressure of port-cells in loss of vacuum accidents (LOVA) and shall limit the VV internal pressure, in the case of loss of coolant (LOCA) or combined accident (LOCA+LOVA). Another important function is mitigation of hydrogen explosion risk collecting hydrogen in the sealed volume of Vapour Suppression Tank.
For these reasons, is important to have a virtual model of the system able to simulate different scenario helping system designers and, in the future, to train plant operators.
Indeed, part of the aim of this PhD thesis is to investigate the applicability of equation-based object-oriented modelling methodology to the problems relevant for nuclear fusion engineering.
To do that EcosimPro has been chosen as system-modelling software for its versatility and availability. Instead, KBC-Multiflash has been used as thermodynamic library. The allow the communication and transfer of information between the two software an intermediate connection has been established. The new platform thus created, is used, first, for the simulation (but also as a benchmark) of the distillation column of the Isotope Separation System of a fusion reactor. Then, the simulation of a vacuum suppression tank of the VVPPSS demonstrates the capabilities of the new platform created (EcosimPro – Multiflash) in terms of customization and flexibility in different applications.

The Thesis is organized as follow:
• Chapter §1 illustrates the subject of the PhD thesis and describes software tool for the modelling of the safety systems of fusion reactors as well as the state of art on equation-based object-oriented modelling (§1.4). The novelty of set up a model-based UV flash calculation is then explained in §1.5.
• Chapter §2 presents the connection between a thermodynamic library (Multiflash) and a library of models (EcosimPro), together with the difficulties addressed during the coding.
Chapter §3 is devoted to the simulation of a cryogenic distillation column applying such connection/platform created. Physical results and optimizations implemented from numerical point of view are introduced as well.
• Chapter §4 discusses the implementation of the phenomena occurring in the VVPSS and the development of a two phase-non equilibrium tank model.
• Chapter §5 reports the conclusions of this work, underlining the results, the achievements and the possible developments of the platform/software created both in fusion nuclear field than in conventional industry.